1. Field of the Invention
The present invention relates to a grooved knife roller for paper shredders. The invention relates specifically to a knife roller having helically extending grooves, wherein the lagging side of each groove in the direction of rotation of the roller and the circumferential surface of the roller include an acute angle to form a hook-like sharp point facing in circumferential direction for cutting paper material in the longitudinal and transverse directions thereof.
2. Description of the Prior Art
Knife rollers in which the circumferential surface of the roller and a lagging side of a groove formed in the roller define an acute angle to form a sharp point are known. The grooves are formed in the surface of the rollers by means of a milling cutting process.
Knife rollers of this type have been found to operate very well in practice. However, they are very difficult and expensive to manufacture. In addition, grinding of the point which is always necessary after longer operation cannot be performed by grinding at the outer circumference of the roller because the points directed radially outwardly from the outer circumference of the roller will become dull and, thus, will lose their cutting capability.
In other known paper shredders, the circumference of a cutting wheel has very long and acute-angled teeth extending from the circumference of the wheel, so that the paper shredders of this type have the additional disadvantage that the teeth can only absorb a very small load.
It is, therefore, the primary object of the present invention to provide a knife roller for paper shredders in which the hook-like sharp point formed by the groove in the roller can be ground from the circumference of the roller without losing the sharp point, and in which an exact transverse cutting is ensured prior to the longitudinal cutting of stacks of paper having any desired thickness. In addition, it should be possible to produce the groove of such a knife roller in a single work step. Also, the sharp point of the knife roller must be capable of absorbing high loads.